| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.5 60/80] sched/uclamp: Reject negative values in cpu_uclamp_write() | Date | Tue, 18 Feb 2020 20:55:21 +0100 |
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From: Qais Yousef <qais.yousef@arm.com>
commit b562d140649966d4daedd0483a8fe59ad3bb465a upstream.
The check to ensure that the new written value into cpu.uclamp.{min,max} is within range, [0:100], wasn't working because of the signed comparison
7301 if (req.percent > UCLAMP_PERCENT_SCALE) { 7302 req.ret = -ERANGE; 7303 return req; 7304 }
# echo -1 > cpu.uclamp.min # cat cpu.uclamp.min 42949671.96
Cast req.percent into u64 to force the comparison to be unsigned and work as intended in capacity_from_percent().
# echo -1 > cpu.uclamp.min sh: write error: Numerical result out of range
Fixes: 2480c093130f ("sched/uclamp: Extend CPU's cgroup controller") Signed-off-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200114210947.14083-1-qais.yousef@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7260,7 +7260,7 @@ capacity_from_percent(char *buf) &req.percent); if (req.ret) return req; - if (req.percent > UCLAMP_PERCENT_SCALE) { + if ((u64)req.percent > UCLAMP_PERCENT_SCALE) { req.ret = -ERANGE; return req; }
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